This invention relates to a method and apparatus for secure traffic light (emergency vehicle changing) interruption. More particularly, the techniques according to the presently described embodiments provide a secure system to allow the interruption of traffic light signals by emergency (and other authorized) vehicles. This is an improvement over the conventional strobe only traffic light interruption (changing) systems. In one form, the presently described embodiments integrate wireless technologies to assure that only authorized users can trigger the traffic light changes that make it safer for emergency vehicles when they approach a traffic light.
While the invention is particularly directed to the art of traffic light interruption, and will be thus described with specific reference thereto, it will be appreciated that the invention may have usefulness in other fields and applications. For example, the invention may be used in other applications where emergency interruption of a system is desired.
By way of background, emergency interruption systems operative to control traffic signals, by permitting interruption by emergency (and other authorized) vehicles, are known. Typically, a system of installed traffic light sensors operate by detecting a rapidly strobing light source approaching from a line of sight distance of up to almost 1,800 feet. The detection devices are normally mounted on the cross bar of the traffic light poles. Once the sensor detects an approaching device, the sensor locks onto the device to determine if preemption should occur.
Some systems simply look for a strobe in any pattern. More advanced systems look for specific strobe patterns before initiating the sequence to change the light.
Referring to FIG. 1, an example of an emergency vehicle 12 entering an area of a traffic light system 10 with an emergency interruption system follows. The system 10 includes a traffic light 14 and a strobe unit or flood lamp system 16, both supported by a structure 18. The vehicle 12 includes a signaling unit 20.
In operation, if the vehicle 12 already has a green light, the light 14 will remain green. Any other direction that also has a green light (usually the opposite direction) will first get a yellow light, then a red light.
When all of the lights of the traffic light 14 facing other directions are turned red, and the vehicle's direction is the only light that is green, the left turn arrow will illuminate (if one exists). A brilliant white flood lamp 16 mounted near the traffic signal 14 will then begin to flash. This flood lamp 16 tells the driver of the fire truck that he now has control of the intersection and, thus, a complete right-of-way.
If the vehicle 12 sees a red light, any other direction that has a green light will transition to a yellow light, then a red light. When the lights facing all the directions (including the fire truck's) are red lights, the traffic signal facing the fire truck will then turn to a green light, along with the left turn arrow (if one exists), and the brilliant white flood lamp 16 will begin to flash.
Once the vehicle 12 has passed through the intersection, optical communication with the preemption detector (on the traffic signal) is lost. At that time, the traffic signal will default back to normal operation. Conversely, until the fire truck passes through the intersection, it will have a green light, regardless of the time duration.
Of course, this is merely one example of a conventional system. Other variations exist.
No matter the form, however, current technology is often circumvented by persons who use a strobe to trick lights into the pass through mode, which is usually reserved for law enforcement or fire personnel. This is a danger to the community and represents a hazard.
More specifically, it has become not too uncommon for non-authorized individuals to purchase emitting devices from online and other retailers. The users install the devices in their cars or other vehicles to change the lights when they do not want to be delayed by the regular sequence of the traffic light. Although this is illegal, it is difficult to identify the person or vehicle. Of course, it could have severe consequences. There have been several accidents across the country already.
The present invention contemplates a new and improved traffic light interruption system that resolves the above-referenced difficulties and others.